igneous

Granite

Phaneritic Felsic Igneous Rock

Hardness: 6-7 on Mohs scale; Color: grey, white, and tan speckled; Luster: dull to vitreous; Crystal structure: phaneritic (large, visible crystals); Cleavage: none (irregular fracture); Specific gravity: 2.63 - 2.75

Hardness: 6-7 on Mohs scale
Color: grey, white, and tan speckled
Luster: dull to vitreous

Identified April 7, 2026More igneous →

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Physical properties

Formation & geological history

Formed from the slow crystallization of magma below Earth's surface. Can range from hundreds of millions to billions of years old, often found in the cores of mountain ranges.

Uses & applications

Extensively used in construction for countertops, floor tiles, paving stones, curbing, monuments, and as crushed stone for road base.

Geological facts

Granite makes up a large portion of the Earth's continental crust. It is one of the hardest natural substances on Earth, and Mount Rushmore is carved into a massive granite batholith.

Field identification & locations

Identify by its interlocking 'salt and pepper' crystalline texture and extreme hardness (it will scratch glass). Commonly found in mountainous regions or areas where ancient bedrock is exposed.

Other igneous specimens

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Blue Apatite

Fluorapatite (Ca5(PO4)3F)

mineral

Dark Igneous Rock (Likely Basalt or Diabase)

Basalt (extrusive igneous rock) or Diabase (intrusive igneous rock - also known as Dolerite), largely composed of plagioclase feldspar, pyroxene (augite), and sometimes olivine and amphibole. Exact mineralogy would require thin section analysis.

Igneous